The present invention relates to a chemical process for multiple utilization of phosphorus ore. More specifically, the process of this invention is especially suitable for dealing with calcareous and calcareous-silicious colloidal phosphorus ore.
Current processes for dressing phosphorus ore involve at least one of the following operations:
grading, floatation and roasting
Normally the combined ore dressing process is adopted. For dressing calcareous colloidal phosphorus ore, the roast process is preferred (see, for example "Using Roast Process in Concentrated Dolomitic Phosphorus Lump Rock Tailings to Produce Light Quality Magnesium Carbonate". "Chemical Mining Technology" June, 1981; P35 China, and "A Summary on medium scale test of phosphorus ore concentration in He Jia Yan, Shaanxi Province", "Chemical Fertilizers and Catalysts", January 1975; p22, China), the tailing thus obtained, however, has a lime white appearance and a high degree of alkalinity (pH=12), creating pollution to the environment, and has an MgO content of 2.5%; the recovery of P.sub.2 O.sub.5 is 78-80%. In order to solve the technical problems in dressing the colloidal phosphorus ore, research has been carried out on chemical ore dressing in the Soviet Union and other countries since 1970s. It is reported that the research undertaken in the Soviet Union is a concentration process by using acid or a sole amine salt to remove MgCO.sub.3 from calcareous colloidal phosphorus ore (see also "The chemical Concentration of Ka La Tao phosphorus ore", Chimical Abstracts 1977, 86, 92552h. The original artical was published on the "Proceedings of the 9th Inorganic Miniral Fertilizer Conference of the National Science and Technology of the Soviet Union" January 1974. p16-17; "The Concentration of coarse partical, magnisium-eontaining Ka La Tao phosphorus ore", which was cited in the same publications as mentioned above). Among all these processes using acid to treat the ore the loss of P.sub.2 O.sub.5 is 7-12%; while using amine salt only, the percentage of magnisium removal is low, the MgO content in the phosphorus concentrate being higher then 1.5%. Thus it fails to realize the multipal utilization of the ore, the regeneration and circulation of the solution. In Japan inorganic acids or amine salts are used to treat the phosphorus ore (see also "The treatment of carbonate apatite", which was published in Japanese opened patent application No. 76718 6, 22nd, June, 1976), it is a direct method for producing combined fertilizer.
Up to now, no success has been reported in increasing the recovery of P.sub.2 O.sub.5, while dressing the colloidal phosphorus ore and reducing the MgO content in phosphorus concentrate, so as to enable the multiple utilization of the ore as well as the prevention of environmental pollution, etc.
The present invention provides a new approach, i.e. to dress the phosphorus ore with an aqueous solution of mixed ammonium salts, and set up, at the same time, a complete enclosed circulation process for by-products recovery and solution regeneration.
It results in the unexpected obtaining of high quality phosphorus concentrate and by-products, the multiple utilization of the ore, increased recovery of P.sub.2 O.sub.5 and solution regeneration without producing tailing, waste gas and water. Thus, it solves the colloidal phosphorus ore dressing problems which remained unsettled for quite a long time.